Distinguishing anemia and iron deficiency of heart failure: signal for severity of disease or unmet therapeutic need?

Despite advances in the management of heart failure (HF), quality of life and other outcomes remain suboptimal for many patients. Anemia and iron deficiency are comorbidities associated with adverse outcomes, although their pathophysiology in the setting of HF is not entirely understood. Anemia and iron deficiency may exist independently and may be a consequence of the systemic inflammatory state characterized by chronic HF. However, it is unclear whether serum hemoglobin concentrations and other hematologic parameters serve as markers for the severity of disease or represent novel therapeutic targets. Research in this area has focused primarily on therapies known to be effective for these conditions in other chronic disease states with similar pathophysiologic features (e.g., end-stage renal disease). Despite its many practical advantages, minimal evidence exists to support the use of oral iron supplementation in this setting. In contrast, intravenous iron has been the subject of several recent investigations, demonstrating improvements in both surrogate and clinical end points, although benefits seem to be the most substantial in patients with concomitant anemia. Erythropoietin-stimulating agents demonstrated early promise in retrospective analyses and small prospective trials, but their benefit was outweighed by a lack of improvement in clinical outcomes and an excess number of thromboembolic events in the largest trial of patients with anemia and HF to date. For acute symptomatic anemia, blood transfusion may be considered, although few trials have included patients with HF, and caution must be exerted in those who are hemodynamically unstable. Based on the currently available evidence, treatment of iron deficiency appears to confer benefit in patients with HF, whereas strategies aimed at improving hemoglobin alone do not. Included is a review of the pathophysiology of these conditions in the setting of HF, clinical trials evaluating pharmacologic therapy, and recommendations for management.